1. Field of the Invention
The present invention relates to a method of manufacturing an electronic device and more particularly to a method of manufacturing an electronic device equipped with a semiconductor integrated circuit, including IC cards, valuable papers, contactless identification devices and the like.
2. Description of the Prior Art
Recently, some electronic devices are estimated to have a promised potential that these devices, including IC cards equipped with an IC chip, a tag, and an identification devices by radio frequency technology, may incorporate a functionality in addition to the recognition of bar codes of the prior technology.
Now an exemplary method of manufacturing an IC card in accordance with the prior technology will be described with reference to FIGS. 14(a) to 14(c). As shown in FIG. 14(a), a thin IC chip 17 will be sucked from a pellet case 142 by means of a vacuum absorber 141. Then the picked up IC chip 17 will be transferred on an IC card substrate 15 (base film) having some adhesive paste applied thereon and pressed on it to fix thereon (see FIG. 14(b)). Thereafter the IC chip 17 attached will be covered by a covering sheet 19, as shown in FIG. 14(c)
Another example of attaching a semiconductor chip onto a base film is disclosed in the Japanese Patent Application Laid-Open No. Hei 08-316194. The method disclosed therein will be described with reference to FIGS. 2(a) to 2(c). In this example, as shown in FIG. 2(a), a plurality of semiconductor chips 17 having an antenna 16 is attached on a supporting sheet, these chips 17 will be pushed on a base film 15 having paste material 14 by means of a press head 21. Thereby the thin IC chips will be transferred and fixed on the film base as shown in FIG. 2(b). FIG. 2(c) is a cross-section indicating the chip and film encapsulated by an adhesive material 18 thereafter.
In the prior techniques as have been described above, the productivity is low because an IC chip is attached one at a time on a substrate. For example, in the method shown in FIGS. 14(a) to 14(c), the improvement of productivity will be limited because each chip is sucked and transferred one at a time. In the prior method shown in FIGS. 2(a) to 2(c), the press head is registered with each of chips to press one by one, the mechanism of assembly machine will become complex. In addition, a certain gap between two adjoining chips will be required during the transfer. This results in a difficulty of lowering the manufacturing cost.
In addition, if the thickness of IC chips to be delivered is for example equal to or less than 10 micrometers, the IC chip will be curled due to the internal stress of the semiconductor material. Thus, this may cause a damage in the chip, which will deform from a curled shape to a plane shape when sucked. In addition, since the chip is very thin, the sucking force of the vacuum sucker may result in a local deformation of the chip, leading to a change of device characteristics by the stress applied to the devices on the chip.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a method of manufacturing an electronic device, suitable for mass production of such devices equipped with a semiconductor integrated circuit.
Another object of the present invention is to provide a method of manufacturing an electronic device, with a lower cost and a higher reliability.
Yet another object of the present invention is to provide a method of manufacturing an IC chip suitable for the method of manufacturing an electronic device as have been described above and ease in processing.
To achieve the object and in accordance with the purpose of the invention, as embodied and broadly described herein, this invention comprises a method of manufacturing an electronic device, comprising the steps of: providing a frame having a plurality of openings on a substrate to be mounted with a semiconductor device, each opening has a dimension suitable to the semiconductor device; providing a plurality of semiconductor devices to the frame to seat one in each of the openings; and fixing the semiconductor devices to the substrate.
By means of a frame having a plurality of openings, a number of semiconductor devices may be supplied to predetermined positions on the substrate at once.
By means of a film-based substrate as the substrate, mass production will be facilitated. In addition, the productivity will be further improved by rolling up and rewinding the base film.
By means of a paper sheet as substrate, the product may be used for the valuables.
To achieve the another object and in accordance with the purpose of the invention, as embodied and broadly described herein, this invention comprises a method of manufacturing an electronic device, comprising the step of: using a thinner IC chip than 30 micrometers for the semiconductor device.
By using a thin film chip, the reliability thereof will be improved due to the strength with respect to the bending stress. The strength with respect to the bending stress may be significant when the thickness is equal to or less than 10 micrometers.
To achieve effectively the yet another object and in accordance with the purpose of the invention, as embodied and broadly described herein, this invention comprises a method of manufacturing an electronic device, comprising the step of: providing a supporting dowel member on the surface or on the backside or on both sides of a thin IC chip.
A support member will improve the resistance to the external stress to facilitate the handling. In particular, the fracture of chips during supplying the thin IC chip onto the frame may be considerably reduced. The thin IC chips will also be placed with a significant certainty on the openings of the frame. Furthermore, the curling of chips when the chips are thinner may be prevented or suppressed.
By forming the semiconductor device in a shape of cube, the resistance to the external stress will be increased to improve the reliability. In particular, the breakage of corner of the chip will be significantly reduced by forming the maximum dimension of 0.5 millimeters or less.
By forming the semiconductor device in a shape of sphere, the resistance to the external stress will be further increased more than a cube form, because no corner exists.
In particular the application of the semiconductor device to a thin electronic device including IC cards, tags, and valuables will be allowed when forming the external dimension of the semiconductor device (length of an edge for a cube and a chip, or diameter for a sphere) equal to or less than 0.5 millimeters.
By providing an optical shielding member on the semiconductor chip, the effect influenced by the incident light to the semiconductor device on the electron-hole pairs may be avoided.
By means of a sheet material having a light shield characteristics for the shield material, the influence by the incident light may be positively avoided. By using printing ink for the shield material, the shield may be formed in an inexpensive manner.
To achieve the yet another object of the present invention, the method in accordance with the present invention comprises the steps of: providing a wall pattern onto the part corresponding to the separating region between semiconductor devices in a semiconductor substrate having a plurality of semiconductor devices; forming a support member having a certain mobility and allowing a bonding after curing onto the part corresponding to the semiconductor devices; and splitting the semiconductor device part into chips.
The mobility of the support member before curing allows the supply at once of the support member to a plurality of inner wall regions surrounded by the wall patterns, therefore improves the productivity. The support member, which can be melted after curing, is particularly suitable to thinner electronic devices because after assembly into an electronic device the member can be melted to reduce the thickness.
By screen-printing of the support member, a mass production will be allowed at a less cost.
By means of a support member of a photosensitive material, the controllability of shapes inherent will allow a mass production.
The above and further objects and novel features of the present invention will more fully appear from following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not intended as a definition of the limits of the present invention.